This invention relates to test machines, and more particularly, to machines for testing the friction characteristics of torque transmitting friction devices.
It is desirable to test friction disc clutch packs, such as those used in automotive transmissions to determined their durability and friction characteristics. Such testing is accomplished by a machine that is commonly termed an SAE #2 Clutch Test Machine. These machines are comprised of an electric motor which is drivingly connected to an inertia load and one set of plates for the disc pack. The other set of discs are restrained from rotation in a housing. The housing is closed by an end cover which serves as a support surface for the friction discs upon engagement by a selectively actuatable piston disposed in the housing.
To conduct the tests on the friction disc pack, the electric motor is rotated at a predetermined speed thereby causing the inertia disc and the rotary portion of the friction disc pack to rotate at that speed. The electric motor is then de-actuated and the friction pack is forced into engagement by the piston causing the rotating discs, the inertia disc and the electric motor to come to a halt.
While the disc pack is being engaged, instruments are utilized to measure various characteristics, such as time, torque transmitted and speed. These performance characteristics can be utilized to determine the operating and friction characteristics of the disc pack. To determine the durability or effective life of a disc pack, a repeatable cycle is imposed on the SAE #2 Machine, such that the disc pack is alternately brought to an operating speed, after which the disc pack is engaged the the system is brought to a halt. This cycle is repeated for a predetermined number of times, after which the friction characteristics of the disc pack are again tested or measured, and the disc pack is visually inspected.
It has been found that the end cover of the test machine can be slightly misaligned during assembly of the disc pack, such that the load imposed by the engaging piston will not be uniform about the periphery of the friction discs. This can lead to reduced operating life and incorrect frictional characteristic calculations. The test machine is designated as a clutch test machine, however, it will provide testing for disc type brake members which are utilized in automatic transmissions also.